Eur. Phys. J. D 1, 169-176 (1998)
https://doi.org/10.1007/s100530050077

Amplification of atomic L-R asymmetries by stimulated emission: experimental demonstration of sensitivity enhancement valuable for parity violation measurements

Laboratoire Kastler Brossel (Laboratoire de l'Université Pierre et Marie Curie et de l'ENS, associé au CNRS (URA 18)) , Département de Physique de l'École Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France

Corresponding author: ^a marianne@physique.ens.fr

Received: 8 October 1997
Accepted: 21 November 1997
Published online: 15 February 1998

Abstract

While all Atomic Parity Violation experiments on highly forbidden transitions in a Stark field have used the detection of fluorescence signals, our group is engaged in an experiment on the cesium transition that uses a pump-probe scheme. The role of the probe beam is to detect the 7S state by stimulated emission. The detected Left-Right asymmetry (A_LR) appears directly on the transmitted probe beam and the technique relies on differential-mode atomic polarimetry. We present here experimental results which illustrate two essential features of this approach. First, A_LR is amplified when the optical thickness for the probe beam is increased, hence it is an increasing function of the Stark field. Secondly, the experimental sensitivity to A_LR is simultaneously increased, as demonstrated by our measurements of the signal-to-noise ratio. We emphasize also the advantage of choosing a probe transition that involves a “dark” state: the A_LR amplification is preserved at high levels of the probe intensity because saturation effects are greatly reduced.